Technical Field
The present disclosure relates to a switching circuit, and in particular, to a power switching circuit.
Description of Related Art
Recently, as the performance of the conventional power semiconductor switch reaches the theoretical limitation of the material itself, technology of the normally-on switching element using wide bandgap power semiconductors such as SiC and GaN semiconductor material are developed rapidly.
However, the drawback of the normally-on switching elements using the aforementioned semiconductor material exists no matter whether a conventional direct driving method is adopted or an indirect driving method with a cascade circuit of a high voltage normally-on switching element and the low voltage normally-off switching element is adopted. For example, in the driving method with the cascade circuit used in recent days, the turn-off speed of the high voltage normally-on switching element is low under the small current, and the bias voltage between the gate and the source of the high voltage normally-on switching element cannot be controlled directly, and thus the risk of the high voltage normally-on switching element being broken down is increased. In addition, due to the significant loss of the reverse recovery by the parasitic capacitance of the low voltage normally-off switching element, so it cannot be applied in high frequency circuits.
Therefore, an important area of research in which to improve the switching response time of the normally-on switching element under different working current requirements, and control the voltage level of the gate of the high voltage normally-on switching element steadily and lower the loss of the reverse recovery at the same time.